Carbohydrate Metabolism Biochemistry and Biomolecules PDF

Carbohydrates Metabolism Keyola McQueen, BSc. MLS  Table of contents I II III Introduction Fructose Galactose Chemistry of Metabolism Metabolism...

Carbohydrates Metabolism Keyola McQueen, BSc. MLS  Table of contents I II III Introduction Fructose Galactose Chemistry of Metabolism Metabolism Carbohydrates IV V Pentose sugars Inborn Errors Metabolism Carbohydrate Metabolism Inborn Errors/ Diseases  Macro-nutrients: ❏ Carbohydrates Glucose ❏ Proteins Amino acids ❏ Triglycerides Glycerol & Fatty Acids What happens when you eat a burger?  Main types of sugars present: ❏ Glucose ❏ Lactose ❏ Galactose ❏ Fructose ❏ Sucrose What sugars are present in a milkshake?  I Introduction Carbohydrates Chemistry  Introduction ❏ Carbohydrates or saccharides are essential components of living organisms. ❏ (C H2O)n Where n=3 or greater. ❏ A single saccharide is called a monosaccharide. ❏ Oligosaccharide is a few linked monosaccharides and are at time associated with proteins (glycoproteins) or lipids (glycolipids) ❏ Polysaccharides consist of many monosaccharides i.e. cellulose or glycogen ❏ Carbohydrates: Main energy sources to body (Brain & red blood cells) ❏ Stored form: Glycogen & Starch ❏ Conversion to fat when in excess ❏ General Molecular Formula for Carbohydrates: Cn(H2O)n ❏ Glucose: C6H12O6 ❏ Absolute configuration: changed configuration of H and OH groups to produce mirror forms ❏ Isomerism of glucose is performed on penultimate carbon atom (D- & L-varieties) ❏ D-variety sugars are naturally occurring ❏ Metabolism can occur on ONLY D-sugars ❏ Monosaccharides can form ring structures ❏ Differences in Aldehyde and Ketone generate -Pyran or -Furan respectively ❏ Metabolism is the overall process through which living systems acquire and utilize free energy to carry out their functions How do living things acquire the energy needed for these functions? ❏ Phototrophs- acquire free energy from sunlight ❏ Chemotrophs - oxidize organic compounds to make ATP II Fructose Metabolism  Biomolecules Organic molecules Hydrolysis Fructose has same molecular Sucrose is hydrolysed by Surase formula as Glucose; the to one mol. Fructose and one structural formula is different mol. Glucose. from Glucose.  Key aspects of Fructose Chemical Organic Medicine processes molecules applications Main source is sucrose Free-form or natural NOT AFFECTED by and high-fructose corn sources of fructose are Insulin; therefore, natural syrups manufactured. honey and fruits. rate in Diabetes Mellitus. Fructose Metabolism Minor pathway of Fructose Metabolism: ❏ Hexokinase act at 6th position (LOW affinity) ❏ Catalysed by Hexokinase & phosphorylated to fructose-6-phosphate ❏ Phosphorylated by Hexokinase in muscle Fructose Metabolism Major pathway of Fructose Metabolism: ❏ Fructokinase present in Liver, intestines and kidneys ❏ Fructokinase act at 1st position (HIGH affinity) ❏ Phosphorylated to fructose-1-phosphate in liver ❏ Fructose-1-P cleaved by Aldolase-B to produce glyceraldehyde & DHAP Fructose Metabolism III Galactose Metabolism  Aspects of Galactose Source Essentials Lactose (milk sugar) UDP Glucose can develop is the major source of UDP Galactose; so not an galactose essential nutrient. Medical Metabolism Applications Metabolised in the Galactose Tolerance liver. Test assesses liver functional capacity Metabolism Major pathway of Galactose Metabolism (Leloir Pathway): ❏ Galactokinase act at 1st position (HIGH affinity) ❏ Catalysed by Galactokinase & phosphorylated to galactose-1-phosphate ❏ Galactose-1-P converted by GALT (rate-limiting enzyme) to Glucose-1-P or UDP Galactose Galactose Metabolism IV Pentoses Metabolism  Features of Pentoses Source Essentials Synthesized from Combines with phosphate glucose-6-phosphate groups and specific bases to form nucleotides Medical Metabolism Applications Pentose phosphate Use of D-ribose in the pathway, thus managing conditions like generates NADPH congestive heart failure, or and intermediates for with athletes anabolic reactions Pentoses Metabolism PPP pathway of Pentose Metabolism: ❏ Pentose Phosphate Pathway takes place in the cytosol ❏ The pathway has two phases: ❏ The oxidative phase: which generates NADPH ❏ The non-oxidative synthesis of five-carbon sugars  V Inborn Errors Inborn Errors of Carbohydrate Metabolism Sir Archibald Garrod (1908) ❏ Developed the concept of “inborn errors of metabolism” ❏ Based on 4 metabolism disorders (e.g. Albinism) ❏ Based on 4 common features: ❏ Congenital ❏ Familial occurrence ❏ Benign conditions ❏ Consanguinity  Inborn Errors of Carbohydrate Metabolism Disturbances of I Fructosuria III Glucose-6-phosphate dehydrogenase II Galactosemia IV Glycogen Storage Diseases Diabetes V Mellitus Pathological Fructosuria Marked fructose intolerance Galactosemia Mental retardation & Jaundice Glycogen Storage Diseases Fasting disorders  Inborn Errors of Metabolism Fructosuria ❏ Benign metabolic defect ❏ Deficiency of Fructokinase ❏ Fructose excretion in urine Galactosemia ❏ Deficiency of GALT ❏ Hypoglycemia ❏ Increased levels of unconjugated bilirubin Glycogen Storage Diseases ❏ Main disease: Type 1 (Von Gierke’s Disease) ❏ Deficiency of Glucose-6-phosphatase ❏ Fasting hypoglycemia ❏ Hyperlipidemia ketosis and childhood deaths. Thanks! 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